Theoretical impossibility results like this one are often interesting because they tell you there is no "smart" way even in practice beyond just brute forcing it.
While it's true that the class of programs that terminate in time at most T is decidable for trivial reasons (just run the program for at most time T), that trivial decider is of course not gonna run in time T (but at least T+1). So if you set T=time until the heat death of the universe, you haven't gained any practical ability to solve the halting problem either.
While it's true that the class of programs that terminate in time at most T is decidable for trivial reasons (just run the program for at most time T), that trivial decider is of course not gonna run in time T (but at least T+1). So if you set T=time until the heat death of the universe, you haven't gained any practical ability to solve the halting problem either.